1. Field of the Invention
The invention relates to the field of marking an area on the body of a patient as a guide for medical treatment. More particularly, the invention relates to marking the skin of a patient in preparation for medical treatment. Most particularly yet, the invention relates to applying marks to the skin of a patient undergoing radiation therapy.
2. Description of the Prior Art
Markings, also often referred to as tattoos, are typically applied to the skin of a patient in preparation for radiation therapy or other medical treatment, as a means of clearly delineating the location of treatment set-up points. Traditionally, the marking is done by applying a drop of marking agent to the surface of the patient's skin and then penetrating the skin with a needle to allow the marking agent to flow under the surface of the skin. The size of the needle used can vary widely, some technicians preferring to work with a larger needle, others with a smaller needle. When marking the skin in this way, it is critical that the marking agent, such as India ink, as well as the needle tip be sterile. Furthermore, it is highly desirable to have a disposable needle, to eliminate the possibility of passing pathogens from one person to another and to eliminate the need for sterilizing the needles. It is also desirable to have a marking device that will accept a standard needle that is typically kept in stock in a healthcare facility, in a range of needle gauges.
Sarath et al. (U.S. Pat. No. 4,798,582; 1989) discloses a needle cartridge that is threadably mounted onto the drive shaft of an electrical tattooing instrument. Chasan (U.S. Pat. No. 5,496,304; 1996) discloses a surgical marking pen for drawing lines on the skin of a patient. The Chasan device has a handle and a fluid reservoir that communicates with a pinwheel that penetrates the skin. Arranged around the circumference of the pinwheel is a plurality of needle tips that puncture the skin, leaving a tattooed line in the epidermis of the skin. The marking pen disclosed therein may be disposable, or refillable. The disadvantages of these devices are that they require special equipment or special needles. The device disclosed in Chasan has the further disadvantage of not being suited for placing individual circular or triangular markings on the skin, that is, it is a device that draws lines, rather than marks points.
Rosen (U.S. Pat. No. 6,056,737; 2000) discloses a disposable skin-marking device that is provided in a sealed sterile package and is discarded after a single use. The skin-marking device has a felt-tip nib and includes a glass cartridge containing marking agent inside a flexible housing. The cartridge is ruptured by bending or compressing the housing, whereupon the marking agent flows into the nib of the pen. This type of device is not suited to applying a marking agent under the surface layer of the skin.
Therefore, what is needed is a skin-marking device for applying a marking agent beneath one or more layers of the skin. What is further needed is such a device that provides a sterile supply of the marking agent and is disposable after a single use. What is still further needed is such a device that accepts a standard general-purpose needle in a range of needle gauges.